Cavity-enhanced optical detection of carbon nanotube Brownian motion

Optical cavities with small mode volume are well-suited to detect the vibration of sub-wavelength sized objects. Here we employ a fiber-based, high-finesse optical microcavity to detect the Brownian motion of a freely suspended carbon nanotube at room temperature under vacuum. The optical detection resolves deflections of the oscillating tube down to 50pm/Hz^1/2. A full vibrational spectrum of the carbon nanotube is obtained and confirmed by characterization of the same device in a scanning electron microscope. Our work successfully extends the principles of high-sensitivity optomechanical detection to molecular scale nanomechanical systems.Comment: 14 pages, 11 figure

Shear-Induced Isotropic-to-Lamellar Transition in a Lattice-Gas Model of Ternary Amphiphilic Fluids

Although shear-induced isotropic-to-lamellar transitions in ternary systems of oil, water and surfactant have been observed experimentally and predicted theoretically by simple models for some time now, their numerical simulation has not been achieved so far. In this work we demonstrate that a recently introduced hydrodynamic lattice-gas model of amphiphilic fluids is well suited for this purpose: the two-dimensional version of this model does indeed exhibit a shear-induced isotropic-to-lamellar phase transition.Comment: 17 pages, LaTeX with epsf and REVTeX, PostScript and EPS illustrations included. To appear in J. Phys. Cond. Ma

Gross karyotypic and phenotypic alterations among different progenies of the candida glabrata cbs138/atcc2001 reference strain

Peer reviewedPublisher PD

Optical detection of a BCS transition of Lithium-6 in harmonic traps

We study the detection of a BCS transition within a sample of Lithium--6 atoms confined in a harmonic trap. Using the local density approximation we calculate the pair correlation function in the normal and superfluid state at zero temperature. We show that the softening of the Fermi hole associated with a BCS transition leads to an observable increase in the intensity of off--resonant light scattered from the atomic cloud at small angles.Comment: 7 pages, 3 figures, submitted to Europhysics Letter

Susceptibility of Cryptococcus neoformans and Cryptococcus gattii from clinical and environment sources in Nairobi, Kenya

Objective: To determine anti-fungal susceptibility of Cryptococcus neoformans andCryptococcus gattii from environmental and clinical sources in Nairobi, Kenya.Design: Prospective study.Setting: Kenya Medical Research Institute, Mycology laboratory, Nairobi, Kenya.Subjects: A total of 123 isolates were tested for their susceptibility to fluconazole(FLC), amphotericin B(AMP) and fluorocytosine (5FC). Clinical isolates were 70(66Cryptococcus neoformans and 4 Cryptococcus gattii) while environmental isolates were53(41 C. neoformans and 12 C. gattii). The isolates were characterised using variousphenotypic tests including microscopic morphology, physiological and biochemicaltests (API 20 Caux), pigmentation on bird seed agar and reaction on canavanineglycine-bromthymolblue agar. European Committee on Anti-microbial SusceptibilityStandards (EUCAST) was used as the reference method for susceptibility testing.Results: Most C. neoformans isolates; clinical (61/66; 92.4%) and environmental (38/41;92.7%) were susceptible to FLC. The number of C. neoformans isolates inhibited atsusceptible dose dependent (SDD) range (16-32μg/ml) by FLC were clinical (4/66; 6.1%)and environmental (2/41; 4.9%). One C. neoformans isolate each; clinical (1/66; 1.5%)and environmental (1/41; 2.4%) was resistant to FLC. All C. gatti isolates from clinicaland environmental were fully susceptible to FLC. The percentage of C. neoformansisolates that were susceptible (S) (MIC ≤ 1.0 μg/ml) to AMP were; clinical(52/66; 90.2%)and environmental (37/41; 78.8%) while the rest were susceptible dose dependent(SDD) with MIC (2-8μg/ml). Reduced susceptibilities to 5FC was displayed in allclinical and environmental C. neoformans and C. gatii isolates; for instance resistanceto 5FC was reported in C. neoformans; clinical (8/66; 12.1%) and environmental (1/41;2.4 %). Among the C. gattii isolates there was also decreased susceptibility to 5FCwith Minimum Inhibition Concentration (MIC) range of between 0.5-32 μg/ml. Therewere no significant differences in susceptibility ranges among all the clinical andenvironmental isolates.Conclusion: This study demonstrated reduced susceptibilities among C. neoformansand C. gattii isolates to commonly used anti-fungal drugs

Glycosylation of Candida albicans cell wall proteins is critical for induction of innate immune responses and apoptosis of epithelial cells.

C. albicans is one of the most common fungal pathogen of humans, causing local and superficial mucosal infections in immunocompromised individuals. Given that the key structure mediating host-C. albicans interactions is the fungal cell wall, we aimed to identify features of the cell wall inducing epithelial responses and be associated with fungal pathogenesis. We demonstrate here the importance of cell wall protein glycosylation in epithelial immune activation with a predominant role for the highly branched N-glycosylation residues. Moreover, these glycan moieties induce growth arrest and apoptosis of epithelial cells. Using an in vitro model of oral candidosis we demonstrate, that apoptosis induction by C. albicans wild-type occurs in early stage of infection and strongly depends on intact cell wall protein glycosylation. These novel findings demonstrate that glycosylation of the C. albicans cell wall proteins appears essential for modulation of epithelial immunity and apoptosis induction, both of which may promote fungal pathogenesis in vivo

Single electron-phonon interaction in a suspended quantum dot phonon cavity

An electron-phonon cavity consisting of a quantum dot embedded in a free-standing GaAs/AlGaAs membrane is characterized in Coulomb blockade measurements at low temperatures. We find a complete suppression of single electron tunneling around zero bias leading to the formation of an energy gap in the transport spectrum. The observed effect is induced by the excitation of a localized phonon mode confined in the cavity. This phonon blockade of transport is lifted at magnetic fields where higher electronic states with nonzero angular momentum are brought into resonance with the phonon energy.Comment: 4 pages, 4 figure

Diffraction of a superfluid Fermi gas by an atomic grating

An atomic grating generated by a pulsed standing wave laser field is proposed to manipulate the superfluid state in a quantum degenerate gas of fermionic atoms. We show that in the presence of atomic Cooper pairs, the density oscillations of the gas caused by the atomic grating exhibit a much longer coherence time than that in the normal Fermi gas. Our result indicates that the technique of a pulsed atomic grating can be a potential candidate to detect the atomic superfluid state in a quantum degenerate Fermi gas.Comment: 4 pages, 2 figure

Candida parapsilosis Colony Morphotype Forecasts Biofilm Formation of Clinical Isolates

Candida parapsilosis is a frequent cause of fungal bloodstream infections, especially in critically ill neonates or immunocompromised patients. Due to the formation of biofilms, the use of indwelling catheters and other medical devices increases the risk of infection and complicates treatment, as cells embedded in biofilms display reduced drug susceptibility. Therefore, biofilm formation may be a significant clinical parameter, guiding downstream therapeutic choices. Here, we phenotypically characterized 120 selected isolates out of a prospective collection of 215 clinical C. parapsilosis isolates, determining biofilm formation, major emerging colony morphotype, and antifungal drug susceptibility of the isolates and their biofilms. In our isolate set, increased biofilm formation capacity was independent of body site of isolation and not predictable using standard or modified European Committee on Antimicrobial Susceptibility Testing (EUCAST) drug susceptibility testing protocols. In contrast, biofilm formation was strongly correlated with the appearance of non-smooth colony morphotypes and invasiveness into agar plates. Our data suggest that the observation of non-smooth colony morphotypes in cultures of C. parapsilosis may help as an indicator to consider the initiation of anti-biofilm-active therapy, such as the switch from azole- to echinocandin- or polyene-based strategies, especially in case of infections by potent biofilm-forming strains.This work was funded in part by grants or scholarships from the ZabaldUz program (Universidad del País Vasco/Euskal Herriko Unibertsitatea) to IDlP, the Consejería de Educación, Universidades e Investigación (GIC15/78 IT-990-16) of Gobierno Vasco-Eusko Jaurlaritza to GQ, the Ministerio de Economía y Competitividad (grants SAF2013-47570-P and SAF2017-86188-P, the latter co-financed by FEDER) of the Spanish government to P.G. and G.Q., and the FP7-PEOPLE-2013-ITN—Marie-Curie Action: “Initial Training Networks”: Molecular Mechanisms of Human Fungal Pathogen Host Interaction, ImResFun, MC-ITN-606786, to O.B. and U.G

Cavity cooling of a nanomechanical resonator by light scattering

We present a novel method for opto-mechanical cooling of sub-wavelength sized nanomechanical resonators. Our scheme uses a high finesse Fabry-Perot cavity of small mode volume, within which the nanoresonator is acting as a position-dependant perturbation by scattering. In return, the back-action induced by the cavity affects the nanoresonator dynamics and can cool its fluctuations. We investigate such cavity cooling by scattering for a nanorod structure and predict that ground-state cooling is within reach.Comment: 4 pages, 3 figure